Chemical analysis systems can include fluidic paths that accommodate high pressures. For example, a liquid chromatography system, such as a system designed for ultra high performance liquid chromatography (UHPLC), can operate at pressures of 15,000 psi or greater. The fluidic paths in such systems often include tubing that is coupled to other components or tubing using a conventional coupling such as a standard compression fitting.
In general, several requirements exist to maintain suitable performance of the chemical analysis system. First, a secure fluidic seal between the coupled elements is required at a low leak rate determined by the desired performance of the chemical analysis system. In addition, the fluidic seal should be sufficiently stable to prevent the release and re-uptake of fluid containing chemical samples or mixtures of samples through the seal interface. Re-uptake can result in carryover, which can significantly degrade system performance. Finally, the unswept volume, or the physical space within the fluid path in which fluid can be trapped and not flushed out by fluid flow, should be minimized. Unswept volume typically occurs between the end of the tubing and the point of seal on a ferrule further back in the fitting assembly. Excessive unswept volume can also result in carryover.